The Anti-Galaxy

What does the opposite of the Milky Way look like? The image above shows one version of it. This image, obtained with the
SPI instrument on the INTEGRAL observatory, shows emission from anti-matter in the Galaxy - in particular it shows gamma-ray emission from electrons colliding and
annihilating with anti-electrons (positrons). The INTEGRAL image shows that unlike matter, which is distributed in the galactic "bulge" and a galactic "disk", antimatter is only concentrated near the center of the Galaxy. The origin of the positrons are not known precisely. Perhaps they are produced by X-ray binaries, or supernovae, or perhaps by some type of exotic dark matter.